Not from the usual acid fog, true, but do bear in mind that any battery
will attract some condensation simply due to its mass and resulting
temperature differential with cabin air.

I've used Optimas in most of my cars for years. Yes, they're expensive
and they're not immortal, but I've got as many as eight years out of
one, and I think that one only died because I neglected it and let it
sit completely discharged for some months. (An advantage of the older
design is that you can sometimes renew them chemically.)

As a matter of tiresome detail, in speaking with my Optima distributor I
learned that the 'gel-cell' label can be a bit misleading. The cells are
liquid-filled; the difference is that the liquid is held in a soft
matrix, making it gel-like. But if the envelope is punctured it'll leak
liquid, so strapping it down is still important.